"Hazards and Control of Noise" Acoustic Phenomenon PPT

Description

"Hazards and Control of Noise" Acoustic Phenomenon PPT

Part One: Preview Perception

1. Source of noise

1. Definition.

(1) From a physical point of view, noise refers to the sound emitted when the sound emitting body does _____________.

(2) From the perspective of environmental protection, all sounds that affect people's _________, _________, and sounds that interfere with the sounds that people want to listen to, are noise.

2. Source.

Examples of noise include _________ on the street, _________ in a quiet library, machinery at a construction site, and the loud sound of a neighbor's television.

2. Noise intensity level and noise hazards

1. Unit.

The unit of sound intensity level is _________, and the symbol is _________.

2. Level.

(1)The weakest sound that can be heard by human ears is _________dB.

(2) In order to ensure rest and sleep, the sound should not exceed _________dB.

(3) In order to ensure work and study, the sound should not exceed _________dB.

(4) In order to protect hearing, the sound should not exceed _________dB.

3. Control noise

1. The sound source.

Prevent noise _________.

2. During the communication process.

_________ that blocks noise.

3. Human ear.

Prevent noise from entering _________.

Noise hazards and control PPT, part 2: interactive classroom understanding

Noise control

[Example] In recent years, square dancing has become a craze across the country. Square dancing is good for physical and mental health, but it also affects the lives of surrounding residents. In order to avoid disturbing the lives of surrounding residents, the correct statement about the following measures is ()

A. Turn down the volume of the speaker so that the pitch of the sound is not too high

B. Residents close doors and windows to reduce noise to human ears

C. Install noise monitoring devices in the square to block the spread of noise

D. Stop dancing in the square after 8:30 pm to prevent noise.

Tips: This question examines the ways to control noise. Answer it according to the following ideas.

Analysis: Adjusting the volume knob of the sound can change the loudness of the sound, but it cannot reduce the pitch of the sound; residents close doors and windows to weaken the noise during the transmission process; installing a noise monitoring device in the square can only monitor and record the noise The situation cannot block the spread of noise; setting time limits and stopping square dancing after 8:30 p.m. can prevent the generation of noise before residents take a break and weaken the noise at the source. Therefore option D is correct.

Answer:D

Noise hazards and control PPT, part 3: try application

1. Source of noise

1. Among the following sounds, the one that belongs to noise is ()

A. While the teacher was giving a lecture, the sound of two students talking

B. The sound of musical instruments at a concert

C. The sound of singers singing at the Spring Festival Gala

D. The voices of classmates answering questions during class

From an environmental protection point of view, any sound that hinders people's normal rest, study and work, as well as any sound that interferes with the sounds people want to listen to, is noise. When the teacher was lecturing, the conversation of two students interfered with the study of other students and was considered noise.

2. The snoring of Xiaoxuan’s father while sleeping was transmitted to Xiaoxuan’s ears through __________, affecting Xiaoxuan’s rest. This kind of sound belongs to _________.

Snoring can be transmitted to people's ears through the air. If the snoring is too loud and affects other people's rest, then the snoring is noise.

2. Noise intensity level and noise hazards

3. The correct understanding of "0 dB" is ()

A.0 dB means the object is not vibrating

B.0 dB is the weakest sound that the human ear can hear

C.0 dB means the frequency is lower than 20 Hz

D.0 dB means the frequency is higher than 20 000 Hz

Decibel is a grade that divides the intensity of sound. It is related to loudness and has nothing to do with pitch, that is, frequency. 0 dB is the lower limit of human hearing, that is, the sound that can just be heard, so the correct option is B.

4. A noise monitoring and decibel display device erected in an urban area is shown in the figure. It can be known from the decibel number displayed on the device ()

A. The noise here can cause people to lose hearing

B. The noise here can hinder people’s work and study

C. The noise at this time hinders people’s rest and sleep

D. The noise at this time is an ideal quiet environment

In order to ensure rest and sleep, the sound should not exceed 50 dB, so the ideal quiet environment is 30~40 dB; in order not to affect work, the sound should not exceed 70 dB. Living in a noise environment above 90 dB will seriously affect your hearing. . From the numbers displayed on the device in the title picture, we can see that the noise at that time was 68 dB, so the noise here will hinder people's rest and sleep.

3. Control noise

5. Noise pollution has become one of the three major pollution hazards to people's lives. Controlling noise pollution should focus on three aspects: preventing noise generation, blocking noise transmission, and preventing noise from entering human ears. Among the following examples, the ones that block noise transmission are ()

This question tests the understanding of specific methods of reducing noise, and the analysis and answer should be combined with the ways and methods of preventing and controlling noise. Stopping construction at the construction site is to prevent and control noise from the generation, which is to reduce the noise at the sound source. Option A does not meet the meaning of the question; residents near the airport use double-layer windows to block the spread of noise, option B meets the meaning of the question; prohibiting cars Honking the horn is to prevent the generation of noise, option C does not meet the meaning of the question; workers wear anti-noise earmuffs when working to prevent noise from entering human ears, option D does not meet the meaning of the question.

6. (2018 Hubei Xiangyang High School Entrance Examination) Noise is one of the pollutions that seriously affects our lives. The following measures belong to the control of noise in the generation process ()

A.Plant trees around the school

B. Cars are prohibited from honking their horns near schools

C. Install soundproof glass in classrooms

D. Install sound insulation panels next to the road near the school

Planting trees around the school, installing soundproof glass in classrooms, and installing soundproof panels next to the road near the school will weaken the noise during the transmission process, so A, C, and D are wrong; banning car horns will weaken the noise where the sound is generated, so B is correct.

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Update Time: 2024-07-04

This template belongs to Physics courseware People's Education Edition Physics for Grade 8, Volume 1 industry PPT template

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